Megakaryocytes and platelets in the spleen of the dromedary camel (Camelusdromedarius)

This study was carried out on spleens of clinically healthy camels (n = 35) of both sexes (0.5-15 years) by routine histology, electron microscopy and immunohistochemistry using 12 anti-bovine platelet antibodies. Megakaryocy tes were observed in the red pulp. Their number decreased with age: they we re found in the spleens of all camels under 8 years old but only in 57% of camels over 8 years old. Only two antibodies (IVA37 and IVA38) cross-reacte d with camel platelets. A large number of platelets were found in the splen ic cords and the marginal zone. Ultrastructurally, the platelets were oval in shape surrounded by a plasma membrane, and their cytoplasm was rich in g lycogen and contained less dense granules. Microtubules and microfilaments were found at their periphery. Several pla telets were observed in the red pulp. There are similarities in some surface antigens of bovine and camel p latelets. The presence of megakaryocytes in the camel spleen indicates a th rombopoietic function of the spleen until adulthood but that this decreases with age thereafter.